This study explores the potentials of a new organotypic culture system as a model for in vivo neural transplants, and as a tool for studying the morphological correlates of synaptic plasticity. I will study the development of embryonic rat hippocampal neurons transplanted to cultured hippocampal slices from neonatal rats. I will observe the process of transplant integration while it happens, using time-lapse 2-photon microscopy. I will observe the effects of slice age and transplant location on the neurite outgrowth of transplanted CA1 and CA3 pyramidal neurons. I will quantify dynamic morphological parameters of the transplanted cells, such as neurite growth and retraction rates, branch formation, and cell body migration, in comparison to those of the host cells. Depolarizing agents will be applied to slices during timelapse imaging to see how the overall level of spontaneous activity in the slice influences neural morphology. The findings will be useful to those interested in the bases of learning and memory, and the potential for hippocampal transplants to ameliorate the effects of neurodegenerative disorders, such as Alzheimer's disease.